Origin of sackung uphill-facing scarps in the Saint Elias orogen, Alaska: LIDAR data visualization and stress modeling

Abstract

Research Article| September 01, 2010 Origin of sackung uphill-facing scarps in the Saint Elias orogen, Alaska: LIDAR data visualization and stress modeling Zhiyong Li; Zhiyong Li 1Faculty of Earth Sciences, China University of Geosciences, Wuhan, 430074, People's Republic of China2Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112, USA Search for other works by this author on: GSW Google Scholar R.L. Bruhn; R.L. Bruhn † 2Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112, USA †E-mail: [e-mail] Search for other works by this author on: GSW Google Scholar T.L. Pavlis; T.L. Pavlis 3Department of Geology, University of Texas, El Paso, Texas 79968-0555, USA Search for other works by this author on: GSW Google Scholar M. Vorkink; M. Vorkink 4GeoStrata, LLC, 781 West 14600 South, Bluffdale, Utah 84065, USA Search for other works by this author on: GSW Google Scholar Zuoxun Zeng Zuoxun Zeng 1Faculty of Earth Sciences, China University of Geosciences, Wuhan, 430074, People's Republic of China Search for other works by this author on: GSW Google Scholar Author and Article Information Zhiyong Li 1Faculty of Earth Sciences, China University of Geosciences, Wuhan, 430074, People's Republic of China2Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112, USA R.L. Bruhn † 2Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112, USA T.L. Pavlis 3Department of Geology, University of Texas, El Paso, Texas 79968-0555, USA M. Vorkink 4GeoStrata, LLC, 781 West 14600 South, Bluffdale, Utah 84065, USA Zuoxun Zeng 1Faculty of Earth Sciences, China University of Geosciences, Wuhan, 430074, People's Republic of China †E-mail: [e-mail] Publisher: Geological Society of America Received: 26 Jan 2009 Revision Received: 14 Jul 2009 Accepted: 04 Sep 2009 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2010 Geological Society of America GSA Bulletin (2010) 122 (9-10): 1585–1599. https://doi.org/10.1130/B30019.1 Article history Received: 26 Jan 2009 Revision Received: 14 Jul 2009 Accepted: 04 Sep 2009 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Zhiyong Li, R.L. Bruhn, T.L. Pavlis, M. Vorkink, Zuoxun Zeng; Origin of sackung uphill-facing scarps in the Saint Elias orogen, Alaska: LIDAR data visualization and stress modeling. GSA Bulletin 2010;; 122 (9-10): 1585–1599. doi: https://doi.org/10.1130/B30019.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Quaternary fault scarps occur in mountain blocks throughout the Saint Elias orogen of southern Alaska. Mechanisms proposed for formation of these scarps include deformation caused by active folding, downhill creep and landsliding on steep, previously glaciated slopes, and superficial faulting caused by strong ground motion during earthquakes. Field observations and interpretation of high-resolution topographic models constructed from a light detection and ranging (LIDAR) survey indicate that failure by flexural toppling creates the uphill-facing scarps in the mountain that we selected for detailed analysis. Toppling failure occurs by shearing and outward rotation of sedimentary bedding that dips steeply into the mountainside. The scarps are therefore created primarily by gravitational stresses, and are not tectonic faults. A three-dimensional finite-element model of the mountain is used to investigate variations in stress field and kinematics of bedding-plane failure by flexural toppling. The results demonstrate the strong influence of mountain morphology on stress orientations and kinematics of shearing along bedding planes. Addition of horizontal compressive tectonic stress may reorient principal stresses caused by gravitational loading, and either enhance or restrict flexural toppling depending upon the angle between bedding surfaces and mountainside. However, modulation of gravity loading by tectonic stress requires the basal sliding surfaces beneath the toppled strata to be either locked or only partly developed. Horizontal acceleration caused by earthquake ground motion and lateral relaxation of mountain flanks following retreat of glaciers also enhance the probability of failure by flexural toppling, especially in the upper parts of mountain slopes, where earthquake ground motion is amplified. The finite-element model does not incorporate these latter two processes, although we discuss their influence in qualitative terms. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.